Oxygen radicals are important regulators in Helicobacter pylori-induced gastric ulceration and carcinogenesis. IL-8 may be regulated by oxidant-sensitive transcription factors, NF-kappaB, and AP-1. The present study aims to investigate whether H. pylori-induced IL-8 expression is regulated by NF-kappaB and AP-1 in gastric epithelial AGS cells and whether this transcriptional regulation of IL-8 is inhibited by N-acetylcysteine (NAC). As a result, H. pylori induced the expression of mRNA and protein for IL-8 via activation of NF-kappaB and AP-1. NF-kappaB activation accompanied by a decrease in I-kappaBalpha and activated AP-1 complex was a c-jun/c-fos heterodimer in H. pylori-infected AGS cells. NAC inhibited H. pylori-induced activation of transcription factors and IL-8 expression in AGS cells. In conclusion, oxygen radicals induce the activation of NF-kappaB and AP-1 and IL-8 expression. Antioxidants such as NAC might be useful anti-inflammatory agents by inhibiting activation of transcription factors and decreasing IL-8 production in H. pylori-induced gastric inflammation.